Safety device for screw jacks



Jan. 8, 1929. 1,698,054

. F. L. GORMLEY ET AL SAFETY 121N103 FOR SCREW JAcxs Filed Jan. 1928 Iiwenlors: Bank L. Gormlcy, fiimfiulik,

Patented Jan. 8, 1929.

'ijhtt FRANK L. GOR-MLEY, OF CHICAGQ AND Jenn some, or HARVEY, trainers, AS-

I SIGNORS TO THE BUDA UGZEZ ANY, OF ILLIITOIS, CORPORATIUN OE rumors.

SAFETY DEVICE BOB, SCREW JACKS.

Application filed' lfann ary 6, 1928. Serial No. 244,859.

This invention relates to safety deyii'es for lifting jacks and particularly for 1o '1'- nal-jacks which are provided with no get) retarding mechanism, the object of ths vention being to prevent the lifting s when worn, from turning and accident lowering the load. I

This object is attained by the mechanism illustrated in the accompanying drawing,

For the purpose of illustrating the invention, one preferred form thereof is illustrated in the drawings, this form having beenfound'to give satisfactory and eliable results, although it is to be understood that the various instrumentalities of which the invention consists can be variously arranged and organized, and the invention is. not limited to the precise arrangement and organization of these instrumentalities' herein shown and described except as required by the scopeof it e appended claims, Of the drawingsfl I Figure 1 represents a vertical section of a lifting jack embodying the principles of the present invention, and I Figure 2 represents apartial horizontal section on line '2, 2, on Fig. 1.;

Similar characters indicate like parts ally throughout the several figures of the drawings.

In the drawings 10 is a casing having a cylindrical hearing at its upper end in which the standard 11 is adapted. to reciprocate;

meshingwithanother bevel gear 1? formed upon the inner end of a driving shaft-:18

revoluble in a bearing in the casing 10 and having an actuating device 19 on the outer end thereof. I

The actuating device used on this driving shaft 18 is that shown in another application of Frank L. Gorrnlcy,"

filed Dec; 21,1926 and numbered 156 105) to which reference may be made as te'construc' tion and operation.

which prefer-sol i's'aline'd and extendin outwardl from the i 7 I b disk superimposed upon a plurality oi? balls 21 disposed in a circular track formed in the upper face of another plate or disk 2" supported upon the removable bottom 23 the casing 10. I a This bottom member 23 I is preferably t readed to the lower part of the casing as i dicated at 24;.

The threads of the lifting screw 15 in a jack of this character must necessarily have a coarse pitch in order to maintain speed when lifting and lowering and still have the jack compact as otherwise it would be necessary to use ears of much greater diameter if the pitch of the screw threads is reduced. This would necessitate making the lower end of the casin of greater diameter, there by increasing the weight of the jack and making it awkward to handle. J

Moreover, it. would be so bulky that it couldnot be used in some places,- especially in close quarters where there would not be, room for the actuating device 19 to be operated to run its standard up to and, from the load to be raised.

With this steep coarse pitch of thread in a screw and its coacting nut 14= a certain amountof wear takes place'between these two member after the jack has been in use some time due to the {frictional contact between the c ontacting screw threads and nut threads. I v i v I This is very objectionable for the reason that as the wear increases thereis a tendency for the standard 11 having a load thereon as it d' lb co cause the screw 15 .o uin an L ieie y ac cidentally lower the load. I I

Some means therefore should be provided in jacks of this character to prevent this accidental lowering and oneway of accomplishing this is showninthe drawings;

To this end the plate 20 has an annular peripheral groove 25 formedtherein-and in this groove 25 is positioned a coil 26 of spring wire having its opposite'ends 27 coil 26." I I These ends 27 are positioned iii holes 38 formed in'the casing 10 and thus prevent any rotation of the coil:26. a 5 When the spring coil 26 is formed its inspring coil 26 and the wall of groove 25 is considerably less than that of the frictional engagement between plate 20 and gear 16.

Consequently under normal conditions the friction spring 26 is suflicient toprevent the rotation ofthe main screw even when a load is on-the standard 11.

hen the actuating device 19 18 used to rotate the screw 15 the plate 20 will rotate frictional contact between the ratchet and with the gear 16 overcoming the friction between spring 26 and the wall of groove 25. When the actuating device 19 is not used to rotate the screw '15, the friction between the spring 26'and plate 20 will be suflicient to prevent any rotation of said screw by pressure exerted thereon by the tendency of the nut 14 to move downwardly under the weight ofthe load upon the standard 11 and this is true even when the screw and nut threads have become wellworn.

'This friction between the spring 26 and plate 20 is also sufficient to overcome the pawl in the actuating device 19 so that the standard 11 may be raised by short strokes of the actuating device 19.

The spring 26 is shown-coactingwith the peripheryof the plate 20 and'this is the preferred form but it is quite obvious that said spring may be applied to some other cylindrical member rotating with the main'screw 15 and accomplish the same results.

It is believedthat the operation and many advantages of the invention will be under stood without further description.

Having thus described our invention, we claim; i

1. In a liftingjack including a casing, a vertically movablestandard, and a rotatable member within the casing for moving said standard having an annular peripheral groove; a non-revoluble member within said groove and in frictional contact therewith.

*2. Ina lifting.jackincluding a casing, "a

' vertically movable standard, and a rotatable member within the casing forinoving said standard I having an annular peripheral. groove;a coiled spring infr ctional contact withthe bottom of said groove with its ends positioned in holes in the wallof said casing.

' yielding means supported by said casing and v I 3." In a lifting jackincluding a standard and a-rotatable steep pitch screw for raising said standard enclosed within a casing; a

cylindrical member rotatable with said screw.

having an annular peripheral groove; and

in frictional cont-act with the bottom ofsaid roove. 1 Y

4. In a lifting jack including a standard and a rotatablesteep pitch screw for raising said standard enclosed within a casing;

a cylindrical member rotatable with said screw; and yielding means supported. by said casing coiled about said member and in frictional contact therewith. I

Ina lifting jack including a standard and a rotatable steep pitch screw for raising said standard enclosed within a casing, said casing having oppositely disposed holes in the wall thereof;a cylindrical member ro- I tatable with said screw having an annular.

7. In a lifting jack including astandard,

a rotatable'steep pitch screw for raising said standard enclosed \Vltlllll a casing and having a driving gear keyed thereto; a bearingplateupon which said gear rests having an annular peripheral groove; and a coiled spring in said groove the normal diameter of which is less than the diameter of said groove and having oppositely extendingiends disposed in holes in said casing;

8. Ina lifting jack, a casing'containing an elevating mechanism consistingin part of a rotatable cylindrical member having an annular peripheral groove; and yielding means supported by said casing and disposed within said groove in frictional contact with the wall thereof.

9. In a lifting jacl a casing containing an elevating mechanism consisting in part of a rotatable cylindrical nieinberhaving an annular peripheral groove: and a non-row oluble springcoiled' round the bottom of said groove'and in frictional contact therewith; v

10. In aIlifting jack, a casing containing an elevating. mechanism consisting in part of a rotatablecylindrical member having an annular peripheral groove; anda-non-revoluble coiled'spring surrounding the bottom of said groove and in frictional, contact therewith, the normal diameter of said coiled spring being less than the diameter of said groove.

Signed by us at Harvey, Illinois, this 3rd day of January, 1928. I e I v FRANK L. GORMLEY.

.JOH'N- BULIK-. 

